High-efficiency heat pumps

ABSTRACT

As discussed herein, a first aspect of the present invention provides a high-efficiency heat pump that includes a frame, as well as a first circuit, a first compressor, a condenser heat exchanger, a first electronic expansion valve, an evaporator heat exchanger, and a controller. The first circuit, the first compressor, the condenser heat exchanger, the first electronic expansion valve, and the evaporator heat exchanger can be supported by the frame. The first compressor, the condenser heat exchanger, the first electronic expansion valve, and the evaporator heat exchanger can be connected to the first circuit. The controller can be in electronic communication with the first electronic expansion valve, and the controller can be configured to control operation of the first electronic expansion valve and/or the second electronic expansion valve.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119(e) to U.S.provisional application 61/108,961, filed Oct. 28, 2008, the entirety ofwhich is hereby incorporated by reference herein.

BACKGROUND

HVAC systems involving water-to-water central heat pumps are becomingmore common. In their most basic form, such systems include a heat pumpthat warms or cools HVAC fluid circulated through pipes within abuilding. A fan blows air from the conditioned space across warmed orcooled coils connected to the pipes. The temperature of the air blownfrom the fan across the coil (typically done by a fan coil unit) is thusaffected by the temperature-controlled HVAC fluid flowing within thepipes. By controlling the temperature and flow rate of the HVAC fluidwithin the pipes, the location and configuration of the pipes and fancoil(s), the speed and capacity of the fan coil(s), and the parametersof various additional equipment that may be incorporated into thesystem, the conditioned space can be maintained at required conditionswith relative ease.

Although heat pump HVAC systems are commonly more efficient thanconventional HVAC systems, they still consume electrical energy tooperate. Differently configured heat pump HVAC systems vary in energyconsumption and efficiency. Most systems do not take advantage ofvarious sources of “free” energy. Additionally, most early heat pumpHVAC systems were slow to respond to building and space load changes andwere more difficult for users to control than conventional HVAC systems.When they thus rely upon backup systems, such as electric duct heaters,they can have relatively high instantaneous electricity demand andoverall higher electricity consumption. The distributed smallcompressors create noise and vibration problems and require continuousHVAC liquid flow rates to stay operational. The total system powerconsumption can become a significant related expense that devalues theenergy and operation cost savings the technology can create.

SUMMARY

In some embodiments, the present invention provides an energy efficientHVAC system that optionally includes a water-to-water heat pump, alongwith one or more components configured to take advantage of unusedenergy sources and/or energy sinks, thereby significantly reducing theamount of energy that is potentially required to be added to the systemfor efficient operation.

In some embodiments, the present invention provides a heat pumpincluding two heat exchangers connected by two or more refrigerationcircuits, with each circuit having an expansion valve and a compressorthat are optionally in electronic communication with a main controller,thereby permitting relatively precise remote control of the heat pump.

In some embodiments, the present invention provides a group ofmulti-circuit water-to-water heat pumps connected together in parallelin a modular fashion, with each circuit of each heat pump having aremotely controllable expansion valve and/or compressor, therebyproviding a highly flexible and responsive heat pump system.

In some embodiments, the present invention provides multiple individualheat pumps and/or groups of heat pumps connected in parallel (seeprevious paragraph) that are connected in series in order to achieve arelatively large temperature difference, with each heat pump or heatpump group being configured to operate within its optimal temperaturerange in incrementally achieving the relatively large temperaturedifference.

In some embodiments, the present invention provides a method ofoperating a multi-circuit heat pump, including (a) receivinginstructions concerning what is needed of the heat pump from a maincontroller based on input from sensors located in various places in theHVAC system and (b) responding to those instructions by activating (ormaintaining activation of) or deactivating (or maintaining deactivationof) one or more compressors in a selected sequence and at selected timeintervals, provided that such response is not restricted based on thedetection of heat pump or HVAC system irregularities.

In some embodiments, the present invention provides a method ofmonitoring for irregularities in heat pumps that are either activated orpending activation to prevent premature wear or failure of heat pumpcomponents and/or to improve energy efficiency in the heat pumps.

In some embodiments, the present invention provides an energy transfercomponent that includes an outer tube made of thermally conductivematerial and a concentric inner tube that can be made of thermallyinsulative material, with (a) HVAC fluid flowing turbulently through thechannel between the inner and outer tubes, optionally guided by aspiraling barrier, such that heat transfer occurs between theturbulently flowing HVAC liquid and the surrounding earth, water, orcombination thereof and (b) HVAC fluid flowing laminarly inside theinner tube, thereby minimizing heat transfer between the HVAC fluidflowing between the inner and outer tubes and the HVAC fluid flowinginside the inner tube.

In some embodiments, the present invention provides system componentsassembled as a modular box, which enables fast and easy installation andreplacement of the modular box, thereby permitting assembly and repairof the distribution equipment in a more suitable setting, such as amachine shop.

In some embodiments, the present invention provides a distributionsystem that optionally accommodates potable water as the HVAC fluid byregularly circulating the potable water through a single coil in a fanbox, that optionally includes a controller, that is in electroniccommunication with a main controller and/or one or more other componentsof the HVAC system.

Details of several aspects and embodiments of the present invention areprovided herein.

Related technology is disclosed in commonly owned U.S. patentapplication Ser. Nos. ______, (filed on Oct. 28, 2009 and titledCONTROLS FOR HIGH-EFFICIENCY HEAT PUMPS [attorney docket no.12524.37.6.2]); ______ (filed on Oct. 28, 2009 and titled METHODS ANDEQUIPMENT FOR GEOTHERMALLY EXCHANGING ENERGY [attorney docket no.12524.37.6.3]); ______, (filed on Oct. 28, 2009 and titled METHODS ANDEQUIPMENT FOR HEATING AND COOLING BUILDING ZONES [attorney docket no.12524.37.6.4]); and ______ (filed on Oct. 28, 2009 and titledHIGH-EFFICIENCY HVAC SYSTEMS AND EQUIPMENT [attorney docket no.12524.37.6.5]). Each of the applications noted in this paragraph arehereby incorporated by reference herein in their entirety.

BRIEF DESCRIPTION OF FIGURES

The following drawings are illustrative of particular embodiments of thepresent invention and therefore do not limit the scope of the invention.The drawings are not to scale (unless so stated) and are intended foruse in conjunction with the explanations in the following detaileddescription. Embodiments of the present invention will hereinafter bedescribed in conjunction with the appended drawings, wherein likenumerals denote like elements.

FIG. 1A is a schematic diagram of a first illustrative HVAC systemaccording to some embodiments of the present invention.

FIG. 1B is a schematic diagram of a second illustrative HVAC systemaccording to some embodiments of the present invention.

FIG. 2 is a schematic diagram of an illustrative dual-circuit heat pumpaccording to some embodiments of the present invention.

FIG. 3A is a flow diagram of an illustrative method for operation of aheat pump according to some embodiments of the present invention.

FIG. 3B is a flow diagram of an illustrative method for protectingagainst damage to the heat pump stemming from heat pump irregularitiesaccording to some embodiments of the present invention.

FIG. 4 is a flow diagram of an illustrative method for assembling a heatpump according to some embodiments of the present invention.

FIG. 5A is a schematic side view of an illustrative flow-through heattransfer component according to some embodiments of the presentinvention.

FIG. 5B is a schematic end view of the flow-through heat transfercomponent of FIG. 5A.

FIG. 6 is a schematic side view of an illustrative ground energytransfer component according to some embodiments of the presentinvention.

FIG. 7 is a schematic view of a distribution box with a control systemmodule according to some embodiments of the present invention.

FIG. 8 is a schematic view of a portion of an HVAC system, including asingle coil within a fan box, according to some embodiments of thepresent invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The following detailed description is exemplary in nature and is notintended to limit the scope, applicability, or configuration of theinvention in any way. Rather, the following description providespractical illustrations for implementing exemplary embodiments of thepresent invention. Examples of constructions, materials, dimensions, andmanufacturing processes are provided for selected elements, and allother elements employ that which is known to those of skill in the fieldof the invention. Those skilled in the art will recognize that many ofthe examples provided have suitable alternatives that can be utilized.

FIG. 1A shows an illustrative HVAC system for heating and/or cooling twozones 2, 4 within the conditioned space 6 of a building. Theillustrative HVAC system includes a heat pump 8, several energy transfercomponents 10, 12, 14, 16, 18, 20, 22, 24, and distribution boxes 26, 28(e.g., with control system modules). The illustrative HVAC system alsoincludes a network of pipes and valves for distributing hot and/or coldHVAC fluid to the various components of the system. In many embodiments,the HVAC fluid can be water (e.g., treated water), an antifreezesolution (e.g., glycol mixed with water), or similar fluids. In someembodiments, the HVAC fluid can be domestic potable water. Individualcomponents of the system are discussed in greater detail elsewhereherein.

It should be emphasized that the HVAC system of FIG. 1A is onlyillustrative. Some buildings include only one zone. Many buildingsinclude more than one zone. Many embodiments of the present inventioncan be incorporated into large buildings with many zones and/or intogroups of buildings with many zones having different embodimentscomplementing the energy balance. HVAC systems can include any suitablecombination of energy transfer components, heat pumps, distributioncomponents, and/or piping/valve distribution systems, based on a varietyof design factors. As is discussed in greater detail elsewhere herein,an HVAC system can include suitable energy transfer component(s) with orwithout a heat pump, with or without distribution component(s), and withor without sections of the illustrated piping/valve distribution system.Similarly, an HVAC system can include one or more suitable heat pumpswith or without energy transfer component(s), with or withoutdistribution component(s), and with or without the illustratedpiping/valve distribution system. Likewise, an HVAC system can includeone or more distribution components with or without energy transfercomponent(s), with or without a heat pump, and with or without theillustrated piping/valve distribution system. As is discussed elsewhereherein, aspects of the illustrated piping/valve distribution system canbe implemented into a variety of HVAC systems. Many embodiments includecomponents other than those shown for taking advantage of sources of“free” energy. Many embodiments include components other than thoseshown for using transferred and free energy, such as snowmelt, radiantheating, domestic hot water, swimming pools, hot tubs, and so on.

The illustrative HVAC system of FIG. 1A includes a heat pump 8. Shownare four stages of the heat transfer cycle: a compressor 336, acondenser heat exchanger 34 rejecting energy, an expansion valve 32, andan evaporator heat exchanger 38 collecting energy. Heat pump refrigerant(e.g., R22, R134a, R407C, etc.) can cycle through the components of theheat pump 8 to reject and absorb heat from the sink and source HVACfluids connected to the HVAC fluid side of the condenser and evaporatorheat exchangers 34, 38. The heat pump refrigerant can circulate andmigrate through the heat pump heat transfer cycle. The cycle can firstbe activated by starting a compressor 36. The work of the compressor 36can compress any residual refrigerant liquid or returning vapor (gas) toa gas of higher pressure and temperature and thus motivate therefrigerant through the cycle. The high pressure and high temperaturerefrigerant can then enter the condenser heat exchanger 34, where theHVAC fluid can cause the refrigerant to condense from gas to liquid asit rejects sensible and latent heat energy to the comparatively coolerhot HVAC fluid. The refrigerant can then enter the expansion valve 32,where the passing refrigerant can be regulated to only an amount whichwill completely vaporize in the spatial volume of the evaporator heatexchanger 38. The suddenly reduced pressure and increased volume in theevaporator heat exchanger 38 can cause the liquid refrigerant to flashto gas and during its change of phase state to absorb its latent heatenergy from the comparatively warmer cold HVAC fluid. The warmed lowpressure refrigerant gas can then return to the compressor 36. Changesin the phase state of the heat pump refrigerant caused by pressure andvolume changes, combined with temperature changes at the condenser heatexchanger 34 and the evaporator heat exchanger 38, can cause heat energyto be “pumped” from the connected cold HVAC fluid to the hot HVAC fluid.

This energy transfer can simultaneously (a) absorb heat energy into theheat pump refrigerant changing from liquid to gas at the evaporator heatexchanger 38, thereby chilling the HVAC fluid at the evaporator heatexchanger 38, and (b) reject heat from the heat pump refrigerant bytemperature difference at the condenser heat exchanger 34, therebyheating the HVAC fluid at the condenser heat exchanger 34. In this way,cooling some HVAC fluid can be the free by-product of heating other HVACfluid, and vice versa, from the same compressor work.

In heating the conditioned space 6, HVAC fluid can exit the heat pump 8through heating loop 40 after passing through the condenser heatexchanger 34 and can then enter the conditioned space 6. In cooling theconditioned space 6, HVAC fluid can exit the heat pump 8 through coolingloop 42 after passing through the evaporator heat exchanger 38.

In some embodiments, components of the heat pump 8 can be selectedand/or configured according to particular applications. In manyembodiments, the heat pump 8 can have two or more refrigerant circuits.FIG. 2 shows an illustrative dual-circuit heat pump 140. The heat pump140 includes an evaporator heat exchanger 142 and a condenser heatexchanger 144. The evaporator heat exchanger 142 can interact with achilled HVAC fluid loop 152 and the condenser heat exchanger 144 caninteract with a hot HVAC fluid loop 154. In this way, the dual-circuitheat pump 140 can provide a similar interface to HVAC systems as doconventional single-circuit heat pumps. In many embodiments,dual-circuit heat pumps can enable paired compressors within the heatpump frame to have separate isolated heat pump refrigerant circuits(avoiding equalization lines), providing staging and better control ofthe refrigerant circuit and conditioning of the HVAC fluid.

Inside the heat pump 140, two separate circuits (circuit A and circuit Bin FIG. 2) can channel heat pump refrigerant through the condenser heatexchanger 144 and the evaporator heat exchanger 142. Circuit A can havea compressor 146A and an expansion valve 148A, and circuit B can have acompressor 146B and an expansion valve 148B. The heat pump refrigerantand its properties in Circuit A may be different than the heat pumprefrigerant and its properties in Circuit B. At any given time,compressors 146A, 146B can both be operational, one of the compressors146A or 146B can be operational, or neither compressor 146A nor 146B canbe operational. In this way, the heat pump 140 can operate at 100%capacity, 50% capacity, or 0% capacity. In this way, the heat pump canbe at peak efficiency when at 100% capacity and when at 50% capacity. Insome embodiments, one or both of the compressors 146A and 146B can bemodulated to provide for greater flexibility in operating capacitypercentage. For example, one or both of the compressors 146A or 146B canbe separately connected to a variable frequency drive; or one or theother of the compressors 146A, 146B can compress an alternaterefrigerant of different properties, or one of the compressors 146A,146B can experience its refrigerant in a different state as caused by adifferent tuning of the expansion valve 148A, 148B. Some heat pumps madeand/or used according to the present invention provide significantenhancements in energy efficient heating and cooling.

In many embodiments, the evaporator heat exchanger 142 and/or thecondenser heat exchanger 144 are plate-and-frame heat exchangers. Heatpump refrigerant and HVAC fluid can be channeled through alternatinggaps between the plates. The plates can be made of thermally conductivematerial in order to facilitate heat transfer between the heat pumprefrigerant and the HVAC fluid. Heat transfer can occur according to thedesign of the heat exchangers 142, 144 and the HVAC system when the heatpump refrigerant and the HVAC fluid are both flowing through therespective gaps between the plates. In many embodiments, such as that ofFIG. 2, the heat pump refrigerant and the HVAC fluid flow through theheat exchangers 142, 144 in opposite directions.

For dual-circuit heat pumps, the heat pump refrigerant from one circuitcan alternate with the heat pump refrigerant from the other circuit whenflowing through the heat exchanger (evaporator 142 or condenser 144). Inmany embodiments, the heat exchangers can be of the brazed plate type,in which case the heat transfer fluids would flow through gaps betweensealed plates. The respective fluids in the heat exchanger gaps wouldalternate between (a) heat pump refrigerant from circuit A, (b) HVACfluid, (c) heat pump refrigerant from circuit B, (d) HVAC fluid, (e)heat pump refrigerant from circuit A, and so on. If both of thecompressors 146A, 146B were operational, both gaps neighboring the HVACfluid would have flowing heat pump refrigerant, meaning that thedesigned heat transfer could occur across each plate. If only one of thecompressors 146A, 146B were operational, only one of the gapsneighboring the HVAC fluid would have flowing heat pump refrigerant,meaning that the designed heat transfer could occur across only half ofthe plates. If neither of the compressors 146A, 146B were operational,neither of the gaps neighboring the HVAC fluid would have flowing heatpump refrigerant, meaning that the designed heat transfer could notoccur across any of the plates. By making operational both, either, orneither of the compressors 146A, 146B, the heat pump can operate at100%, 50%, or 0% capacity.

In some embodiments, the absorption of heat from the HVAC fluid in theevaporator heat exchanger 142 in one or both of the heat pump circuitscan be controlled via the expansion valves 148A, 148B. In manyembodiments, the expansion valves 148A, 148B can be electronic expansionvalves, which can control the superheat from the evaporator heatexchanger 142 across a broad range of valve percentages (e.g., from 0%to 100%). Many electronic expansion valves can react faster and moreprecisely to changing conditions in the evaporator heat exchanger 142than a conventional expansion valve. Some electronic expansion valvescan be configured to communicate electronically with an operator and/ora controller through a network (e.g., the Internet). In this way, theelectronic expansion valves can be monitored and adjusted remotely.Often, the precise control of electronic expansion valves' superheatsetting provides significant savings on operational costs. The highrange of valve control and internal programming can enable continuousoperation over a wider range of conditions from ice making to hot waterheating on the same common refrigerant charge.

The performance of the dual-circuit heat pump 140 can be impacted by avariety of factors. As noted above, in some embodiments, the number ofcompressors 146A, 146B that are operational (along with, in someembodiments, modulation of one or both of the compressors 146A, 146B)can impact the performance of the heat pump 140. As also noted above,the pressure of the heat pump refrigerant in one or both of thecircuits, as controlled via the expansion valves 148A, 148B, can impactthe performance of the heat pump 140. In some embodiments, the selectionof the heat pump refrigerant can impact the performance of the heat pump140. Different heat pump refrigerants change states at differenttemperatures and pressures. The overall efficiency of the heat pump 140can be affected by the characteristics of the refrigerant, including theenergy absorbed or given off during a change of state. Thus, theselection of a heat pump refrigerant can have a significant impact on,e.g., the temperature difference across the heat pump 140 and the workinput to motivate the temperature difference. In some embodiments, thevolume of heat pump refrigerant added to either or both of the circuitscan impact the performance of the heat pump 140. In some embodiments,the volume of oil in the heat pump refrigerant can impact performance ofthe heat pump 140. One or more of these and similar factors can becontrolled to provide optimal heat pump performance, depending on thecircumstances of the particular application. In some embodiments, thedual-circuit heat pump can reduce the number of mechanical connectionsand fittings for the HVAC fluids, thereby reducing flow restrictionswhile at the same time increasing performance.

In many embodiments, the heat pump 140 is designed and/or configured toproduce repeatable temperature differences across the respective heatexchangers 142, 144. In some instances, flow properties of the HVACfluid in the chilled HVAC fluid loop 152 and/or the hot HVAC fluid loop154 can be adjusted with control valves 156, 157, 158, 159 to achievetemperature differences across the heat exchangers 142, 144 that differfrom those that would have been achieved in absence of the adjustmentwith the control valves 156, 157, 158, 159. In some embodiments, apercentage of the HVAC fluid can bypass a heat exchanger by means of oneor more bypass valves.

In some embodiments, multiple heat pumps 140 are made in modularfashion, such that each heat pump 140 is a self-contained unit withclearly defined interfaces to other HVAC system components, includingother heat pumps. Such a setup can provide a significant degree offlexibility in operating capacity percentage. The number of heat pumps(and specifically the number of compressors) is directly related to thenumber of operating capacity levels. The number of operating capacitylevels is equal to the number of compressors plus one (accounting for 0%operating capacity). For example, with five dual-circuit heat pumpsconnected in parallel, there are eleven operating capacity levels.Assuming that all five heat pumps have similar configurations, the heatpumps collectively can operate at 0% (none of the compressorsoperational), 10% (one of the ten compressors operational), 20% (two ofthe ten compressors operational), and so on. The HVAC fluid flow canhave equivalent capacity levels of reduced pumping energy with eachrefrigerant circuit still operating at optimum capacity and efficiency.In this way, the heat pumps collectively can provide what the HVACsystem demands in a more precisely tailored fashion, therebysignificantly improving energy efficiency.

As discussed herein, a first aspect of the present invention provides ahigh-efficiency heat pump that includes a frame, as well as a firstcircuit, a first compressor, a condenser heat exchanger, a firstelectronic expansion valve, an evaporator heat exchanger, and acontroller. The first circuit, the first compressor, the condenser heatexchanger, the first electronic expansion valve, and the evaporator heatexchanger can be supported by the frame. The first compressor, thecondenser heat exchanger, the first electronic expansion valve, and theevaporator heat exchanger can be connected to the first circuit.

In the first aspect, the first circuit can be configured to circulate afirst refrigerant. The first compressor can be configured to (i) receivethe first refrigerant from the first circuit, (ii) increase pressure ofthe first refrigerant, and (iii) provide the higher-pressure firstrefrigerant back to the first circuit. The condenser heat exchanger canbe configured to (i) receive the higher-pressure first refrigerant fromthe first circuit, (ii) transfer energy from the higher-pressure firstrefrigerant to a first HVAC fluid passing through the condenser heatexchanger, and (iii) provide the first refrigerant back to the firstcircuit. The first electronic expansion valve can be configured to (i)receive the first refrigerant from the first circuit, (ii) decreasepressure of the first refrigerant, and (iii) provide the lower-pressurefirst refrigerant back to the first circuit. The evaporator heatexchanger can be configured to (i) receive the lower-pressure firstrefrigerant from the first circuit, (ii) transfer energy from a secondHVAC fluid passing through the evaporator heat exchanger to thelower-pressure first refrigerant, and (iii) provide the firstrefrigerant back to the first circuit.

In the first aspect, the heat pump may include a second circuit, asecond compressor, and a second electronic expansion valve, eachsupported by the frame. The second circuit can be configured tocirculate a second refrigerant. The second compressor and the secondelectronic expansion valve can be connected to the second circuit. Thesecond compressor can be configured to (i) receive the secondrefrigerant from the second circuit, (ii) increase pressure of thesecond refrigerant, and (iii) provide the higher-pressure secondrefrigerant back to the second circuit. The condenser heat exchanger canbe further configured to (i) receive the higher-pressure secondrefrigerant from the second circuit, (ii) transfer energy from thehigher-pressure second refrigerant to HVAC fluid passing through thecondenser heat exchanger, and (iii) provide the second refrigerant backto the second circuit. The second electronic expansion valve can beconfigured to (i) receive the second refrigerant from the secondcircuit, (ii) decrease pressure of the second refrigerant, and (iii)provide the lower-pressure second refrigerant back to the secondcircuit. The evaporator heat exchanger is further configured to (i)receive the lower-pressure second refrigerant from the second circuit,(ii) transfer energy from HVAC fluid passing through the evaporator heatexchanger to the lower-pressure second refrigerant, and (iii) providethe second refrigerant back to the second circuit.

In the first aspect, the controller can be in electronic communicationwith the first electronic expansion valve and/or the second electronicexpansion valve. The controller can be configured to control operationof the first electronic expansion valve and/or the second electronicexpansion valve.

In the first aspect, the high-efficiency heat pump may include one ormore of the following features. The controller may be configured tomodulate the first and second compressors. At least one of the condenserheat exchanger and the evaporator heat exchanger can be aplate-and-frame heat exchanger with gaps between plates. In some suchembodiments, the first and second circuits can be connected to theplate-and-frame heat exchanger so as to channel the first refrigerant,HVAC fluid, the second refrigerant, and HVAC fluid, respectively,through alternating gaps. The first refrigerant and the secondrefrigerant can be different refrigerants having different properties.The first electronic expansion valve can be configured to communicateelectronically with an operator and/or a remote controller through anetwork. The controller can be configured to receive input from one ormore sensors of an HVAC system that incorporates the heat pump. In somesuch embodiments, the controller can be configured to control operationof the first electronic expansion valve based on that input. The firstexpansion valve can be controllable to (a) simultaneously heat the firstHVAC fluid to a temperature above 100F and cool the second HVAC fluid toa temperature below 10F in a first season and (b) simultaneously heatthe first HVAC fluid to a temperature above 160F and cool the secondHVAC fluid to a temperature below 40F in a second season. In someembodiments, the heat pump can further include a third compressor and athird electronic expansion valve, both supported by the frame, as wellas a third circuit supported by the frame and configured to circulate athird refrigerant through the third compressor, the condenser heatexchanger, the second electronic expansion valve, and the evaporatorheat exchanger.

As discussed herein, a second aspect of the present invention provides amethod of efficiently heating and/or cooling HVAC fluid. The method caninclude providing a high-efficiency heat pump, such as the heat pumpdiscussed in connection with the first aspect or other heat pumpsdiscussed herein. The method can include circulating a first HVAC fluidthrough the condenser heat exchanger or the evaporator heat exchanger.The method can include activating the first compressor to heat the firstHVAC fluid if the first HVAC fluid is circulating through the condenserheat exchanger or to cool the first HVAC fluid if the first HVAC fluidis circulating through the evaporator heat exchanger. The method caninclude controlling the first electronic expansion valve to controlheating of the first HVAC fluid if the first HVAC fluid is circulatingthrough the condenser heat exchanger or to control cooling of the firstHVAC fluid if the first HVAC fluid is circulating through the evaporatorheat exchanger.

In the second aspect, the method of efficiently heating and/or coolingHVAC fluid may include one or more of the following features. The methodmay include circulating a second HVAC fluid through whichever of theheat exchangers the first HVAC fluid is not circulating through. In somesuch embodiments, activating the first compressor simultaneously heatsthe HVAC fluid in the condenser heat exchanger to a temperature above125F and cools the HVAC fluid in the evaporator heat exchanger to atemperature below 35F. In some such embodiments, activating the firstcompressor simultaneously heats the HVAC fluid in the condenser heatexchanger to a temperature above 130F and cools the HVAC fluid in theevaporator heat exchanger to a temperature below 30F. In embodimentshaving a dual-circuit heat pump, the method can include activating boththe first compressor and the second compressor to heat the first HVACfluid if the first HVAC fluid is circulating through the condenser heatexchanger or to cool the first HVAC fluid if the first HVAC fluid iscirculating through the evaporator heat exchanger. In some embodiments,controlling the first electronic expansion valve comprises remotelycontrolling the first electronic expansion valve. In some suchembodiments, remotely controlling the first electronic expansion valvecomprises controlling operation of the first electronic expansion valvebased on input from one or more sensors of an HVAC system thatincorporates the heat pump.

As discussed herein, a third aspect of the present invention provides amethod of efficiently heating and/or cooling HVAC fluid. The method caninclude providing at least two heat pump units, such as those discussedin connection with the first aspect or other heat pumps discussedherein. The method can include connecting the heat pump units inparallel to create a heat pump. The method can include circulating afirst HVAC fluid through the condenser heat exchanger or the evaporatorheat exchanger of at least one of the heat pump units. The method caninclude activating the first compressor of at least one of the heat pumpunits to heat the first HVAC fluid if the first HVAC fluid iscirculating through the condenser heat exchanger(s) or to cool the firstHVAC fluid if the first HVAC fluid is circulating through the evaporatorheat exchanger(s). The method can include controlling the correspondingfirst electronic expansion valve(s) to control heating of the first HVACfluid if the first HVAC fluid is circulating through the condenser heatexchanger(s) or to control cooling of the first HVAC fluid if the firstHVAC fluid is circulating through the evaporator heat exchanger(s).

In the third aspect, the method of efficiently heating and/or coolingHVAC fluid may include one or more of the following features. The methodcan include circulating a second HVAC fluid through the whichever of theheat exchangers of the at least one heat pump unit the first HVAC fluidis not circulating through. In some such embodiments, activating thefirst compressor of the at least one heat pump unit simultaneously heatsthe HVAC fluid in the condenser heat exchanger(s) to a temperature above125F and cools the HVAC fluid in the evaporator heat exchanger(s) to atemperature below 35F. In some such embodiments, activating the firstcompressor of the at least one heat pump unit simultaneously heats theHVAC fluid in the condenser heat exchanger(s) to a temperature above130F and cools the HVAC fluid in the evaporator heat exchanger(s) to atemperature below 30F. The method can include activating firstcompressors of multiple heat pump units. In some embodiments,circulating the first HVAC fluid through the condenser heat exchanger orthe evaporator heat exchanger of at least one of the heat pump unitscomprises circulating the first HVAC fluid through the condenser heatexchanger or the evaporator heat exchanger of fewer than all of the heatpump units. In some embodiments, the first HVAC fluid enters the heatpump through a common inlet, then diverges to at least two separate heatpump units, and then converges to exit the heat pump through a commonoutlet. In embodiments having a dual-circuit heat pump, the method caninclude selectively activating the second compressor of at least one ofthe heat pump units to heat the first HVAC fluid if the first HVAC fluidis circulating through the condenser heat exchanger(s) or to cool thefirst HVAC fluid if the first HVAC fluid is circulating through theevaporator heat exchanger(s). Controlling the corresponding firstelectronic expansion valve(s) can include remotely controlling at leastone of the corresponding first electronic expansion valve(s). In somesuch embodiments, remotely controlling at least one of the correspondingfirst electronic expansion valve(s) comprises controlling operation ofthe at least one of the corresponding first electronic expansionvalve(s) based on input from one or more sensors of an HVAC system thatincorporates the heat pump.

Heat pumps according to the present invention can be controlled in avariety of ways. FIGS. 3A-3B show illustrative methods for controllingdual-circuit heat pumps (such as the heat pump of FIG. 2). FIG. 3A showsan illustrative method for operation of the heat pump, based oninstructions provided regarding what is needed from the heat pump. FIG.3B shows an illustrative method for monitoring for heat pumpirregularities and triggering the heat pump to turn off in the eventthat one or more of such irregularities is detected.

Referring to FIG. 3A, the time variables (e.g., the heat pump time onand time off variables) of the heat pump can be set (200). The automaticcontrols can measure and record the time duration a particular heat pumphas been on or the time duration a particular heat pump has been off.Outputs from the main controller 202 of the HVAC system can send asignal to the heat pump controller indicating what is needed of the heatpump (204). Sensors positioned throughout the HVAC system can provideinput to the main controller 202 concerning the conditions of the HVACfluid. For example, referring to FIG. 1A, the main controller of theHVAC system can receive input from a temperature sensor reading thetemperature of the returning hot HVAC fluid. The main controller cancompare the desired conditions with the actual conditions and determinewhat role the heat pump can play in bringing the actual conditions intoconformity with the desired conditions. The main controller can generateinstructions concerning the role of the heat pump and can provide thoseinstructions to the heat pump controller, as indicated by step (204) ofFIG. 3A.

Referring again to FIG. 3A, the instructions provided by the maincontroller 202 to the heat pump controller (204) can relate to one ormore of several variables of the heat pump. The operation of a heat pumpcontroller can be overridden and supervised automatically by the maincontroller 202 or manually (e.g., by the building operator) at the heatpump, at a local computer monitoring the HVAC system, or through anetwork, such as the internet. For example, the instructions canmanually deactivate a heat pump for servicing. The operations of anexpansion valve controller can be overridden and supervisedautomatically by the main controller 202 or manually (e.g., by thebuilding operator) at the heat pump, at a local computer monitoring theHVAC system, or through a network, such as the internet. For example,the instructions can change the superheat setpoint.

In many embodiments, the instructions call for the activation ordeactivation of one or both of the heat pump's compressors. The heatpump controller can determine whether the instructions call fordeactivation of both compressors (deactivate if activated or remaindeactivated if already deactivated) (206). If the heat pump controllerdetermines that the instructions indeed call for deactivation of bothcompressors, the heat pump controller can signal both compressorsaccordingly (208, 210), which can result in both compressors beingstopped (212, 214). If the heat pump determines that the instructionscall for activation of at least one compressor (activate if deactivatedor remain activated if already activated), the heat pump can move to thenext level of analysis.

If the heat pump controller determines that the instructions call foractivation of at least one of the compressors, the heat pump controllercan determine whether the instructions call for activation of only oneof the compressors (216) or activation of both of the compressors (218).If the heat pump controller determines that the instructions call foractivation of only one of the compressors, the heat pump controller cansignal activation of either compressor A (220) or compressor B (222).This can result in a call of compressor A (224) or compressor B (226),pending inspection for irregularities (described in greater detailbelow). Whichever compressor is not called is/remains deactivated (212,214).

When instructions call for activation of only one compressor, the heatpump controller can call either compressor A or compressor B based on analternating or priority wear schedule. If either compressor A orcompressor B were always called in this situation, that compressor wouldwear significantly faster than the other. Accordingly, a schedule can beestablished to encourage even wear of the two compressors or thepreservation of one of the components. The digital control of theembodiment can enable many scheduling variations. In some embodiments,the heat pump controller determines which of the compressors to call. Insome embodiments, the main controller determines which of the twocontrollers to call.

When the heat pump controller determines that the heat pump controllercalls for activation of both compressors, the heat pump controller cansignal activation of the compressors in a staggered fashion. In someinstances, the heat pump controller can signal activation of compressorA first, followed by activation of compressor B after a time delay(228). This can result in (a) a call of compressor A (224), pendinginspection for irregularities, (b) a period of delay as determined byreduced Amperage of the first stage and verification after the delay ofa continued need, and (c) a call of compressor B (226), pendinginspection for irregularities. In some instances, the heat pumpcontroller can signal activation of compressor B first, followed byactivation of compressor A after a delay (230). This can result in (a) acall of compressor B (226), pending inspection for irregularities, (b) aperiod of delay and confirmations, and (c) a call of compressor A (224),pending inspection for irregularities. Which compressor to activatefirst is often determined according to a schedule designed to reduce thelikelihood of uneven wear between the compressors or overall long-termreliability of the system. The heat pump controller and/or the maincontroller can make this determination in a manner similar to thedetermination of which compressor to call when only one compressor isrequested.

In some embodiments, the call for activation of a compressor can openthe source valve SV for the cold HVAC fluid to the evaporator heatexchanger and open the load (moderate) valve MV for the hot HVAC fluidto the condenser heat exchanger. In many embodiments, the valves willclose when both compressors are off. Operating the valves in this mannercan reduce the pumping costs of the system, enable modules to operate atlower system flows, and prevent refrigerant migrations within the heatpump system from occurring when the heat pump is not active.

As alluded to above, before activating one or both of the compressors,the heat pump can be inspected for one or more irregularities (232,234). Such an inspection can also be called a safety inspection inreference to making sure that activation of the compressor(s) will notdamage the heat pump. If the heat pump controller determines thatactivation of either of the compressors (232, 234) would be unsafe, theheat pump controller can disable the activation of the compressor(s)(212, 214). If the heat pump controller determines that activation ofone or both compressors would not be unsafe (232, 234), the heat pumpcontroller can proceed with activation of the compressor(s) (236, 238).

FIG. 3B shows an illustrative method of monitoring for heat pumpirregularities and/or heat pump safety concerns. As can be seen, themethod of FIG. 3B includes eight tests. Other methods according to thepresent invention may include a greater or lesser number of tests. Othermethods according to the present invention may involve one or more ofthe tests illustrated in FIG. 3B in a different order. A variety oftests, combinations, and orders are possible.

The heat pump controller can first activate the method (250). When acompressor is called, but before the compressor is turned on, the methodcan be activated. If the method detects no irregularities, thecompressor can be turned on. In many embodiments, while the compressoris turned on, the method can run on a continuous basis. In suchembodiments, if the method detects an irregularity or safety concernwhile the compressor is operating, the heat pump controller can causethe compressor to be deactivated. In most embodiments, the method ofFIG. 3B can be performed in a relatively short period of time (e.g.,once per second) to accommodate active compressors.

In many embodiments, the method of FIG. 3B supplements, or issupplemented by, protections that are hard-wired into the heat pumpcomponents themselves. The hard-wired protections can monitor for someor all of the irregularities that are monitored for by the heat pumpcontroller. In many such embodiments, the heat pump controller safetytests are more conservative than those of the hard-wired heat pumpcomponents. In many such embodiments, the heat pump controller safetytests and the hard-wired safety tests can serve as back ups to oneanother in the event that one of the safety tests does not properlydetect a potentially damaging heat pump irregularity.

With the method in active mode, the heat pump controller can run avariety of safety tests. One test can prevent compressors from beingsubjected to repeated short cycles (252). A compressor subjected torepeated short cycles can wear prematurely or be damaged. Embodiments ofthe present invention can prevent short cycles, thereby reducing thelikelihood of premature wear of the compressor or heat pump failure. Theheat pump controller can determine whether a compressor was justrecently deactivated (e.g., within the past 10 or 15 minutes). In such asituation, the heat pump controller typically delays activation of thecompressor to give it an appropriate amount of recovery (e.g., 10-15minutes). Given the large size of most HVAC systems and given the factthat gradual changes in space conditions are typically desirable, thedelay in activation of one compressor does not typically impedeperformance of the HVAC system.

If the heat pump controller determines that the compressor was recentlydeactivated, the heat pump controller can generate an alarm signal,signifying a condition in which operation of the compressor would beunsafe to the compressor (254). If the test identifies a potentiallyunsafe short cycle in compressor A, the unsafe condition is associatedwith compressor A (256). If the test identifies a potentially unsafeshort cycle in compressor B, the unsafe condition is associated withcompressor B (258). Referring to FIG. 3A, unsafe conditions associatedwith the respective compressors are shown (256, 258). As alluded toabove, if either of these inputs (256, 258) indicate an unsafecondition, activation of the corresponding compressor will be prevented.

Referring again to FIG. 3B, if the heat pump controller determines thatactivating the called for compressor would not result in a potentiallyunsafe short cycle, the heat pump can administer additional safetytests. Another test monitors for irregular or inappropriate current drawexperienced by the relevant compressor (260). Inappropriate current drawcan result from, e.g., a change in load, a faulty power supply, andother reasons. If the heat pump controller detects an irregular orinappropriate current draw, the heat pump controller can generate a“high” signal, signifying a condition in which operation of thecompressor would be unsafe to the compressor (254). As is discussedelsewhere herein, this condition can be associated with a compressor,which can prevent activation of, or deactivate, that compressor.

The third test of the illustrative method of FIG. 3B monitors forabnormally low suction pressure (262). This test can activate an alarmif the evaporator inlet refrigerant pressure is below a determined safelevel that would cause “slugging” or fluidized refrigerant in damagingamounts to enter the compressor. If allowed to enter the compressor,mechanisms can be bent or broken. If the heat pump controller detects anabnormally low suction pressure, the heat pump controller can generate a“low” signal, signifying a condition in which operation of thecompressor would be unsafe to the compressor (254). As is discussedelsewhere herein, this condition can be associated with a compressor,which can prevent activation of, or deactivate, that compressor.

The fourth test of the illustrative method of FIG. 3B monitors forabnormally high delivery pressure (264). This test can activate an alarmif the condenser outlet refrigerant pressure is above a determined safelevel that would cause overheating and burning of the compressorwindings. If allowed to over-pressurize, the compressor can beirreparably damaged. If the heat pump controller detects abnormally highdelivery pressure, the heat pump controller can generate a “high”signal, signifying a condition in which operation of the compressorwould be unsafe to the compressor (254). As is discussed elsewhereherein, this condition can be associated with a compressor, which canprevent activation of, or deactivate, that compressor.

The fifth test of the illustrative method of FIG. 3B monitors forabnormally low source temperature (266). This test can activate an alarmif the leaving HVAC fluid temperature is below a predetermined minimumthat can cause the HVAC fluid in the evaporator to freeze or “gel”creating a “freeze rupture” in the heat pump condenser. This event canlead to a splitting of the plates in the condenser heat exchanger andleakage, a blockage of the HVAC fluid flow, and low suction pressure ofthe refrigerant flow. If the heat pump controller detects abnormally lowsource temperature, the heat pump controller can generate a “low”signal, signifying a condition in which operation of the compressorwould be unsafe to the compressor (254). As is discussed elsewhereherein, this condition can be associated with a compressor, which canprevent activation of, or deactivate, that compressor.

The sixth test of the illustrative method of FIG. 3B monitors forabnormally high load temperature (268). This test can be activated ifthe hot HVAC fluid leaving the heat pump condenser is above apredetermined set point. If the leaving hot HVAC fluid is too hot, itcan lead to unsafe fluid temperatures in the HVAC system with thepotential for burning skin, damaging piping, activating secondaryalarms, and other events. In the event of high load temperature, thecompressor is deactivated until a predetermined reset level is achieved.If the heat pump controller detects abnormally high load temperature,the heat pump controller can generate a “high” signal, signifying acondition in which operation of the compressor would be unsafe to thecompressor (254). As is discussed elsewhere herein, this condition canbe associated with a compressor, which can prevent activation of, ordeactivate, that compressor.

The seventh test of the illustrative method of FIG. 3B monitors for anabnormal positioning of the source valve (270). This test can activatean alarm if the heat pump compressors are called to turn on and thesource valve is not in a position to allow flow of the HVAC fluidthrough the heat pump evaporator. If undetected, this event could causesecondary alarms (noted elsewhere herein) that would be caused by lowsuction and subsequent freeze rupturing. If the heat pump controllerdetects an abnormal positioning of the source valve, the heat pumpcontroller can generate an “alarm” signal, signifying a condition inwhich operation of the compressor would be unsafe to the compressor(254). As is discussed elsewhere herein, this condition can beassociated with a compressor, which can prevent activation of, ordeactivate, that compressor.

The eighth test of the illustrative method of FIG. 3B monitors for anabnormal positioning of the load valve (272). This test can activate analarm if the heat pump compressors are called to turn on and the loadvalve is not in a position to allow flow of the HVAC fluid through theheat pump condenser. If undetected, this event could cause secondaryalarms as noted herein that would be caused by high discharge pressureand subsequent compressor overheating. If the heat pump controllerdetects an abnormal positioning of the load valve, the heat pumpcontroller can generate an “alarm” signal, signifying a condition inwhich operation of the compressor would be unsafe to the compressor(254). As is discussed elsewhere herein, this condition can beassociated with a compressor, which can prevent activation of, ordeactivate, that compressor.

Monitoring for heat pump irregularities, e.g., by the illustrativemethod shown in FIG. 3B, can provide a variety of advantages. Somemethods can assure health and safety measures related to the temperatureof the HVAC fluid. Some methods can attract attention to other failuresin the overall HVAC system. Some methods can help in the long-termcontrol of the HVAC system. Some methods can prevent permanent damageand premature wear of the compressors or other components of the heatpump and secondary components in the HVAC system. Some methods canmaintain and provide increased energy efficiency of the heat pump andthe HVAC system.

Many heat pump embodiments described herein can be assembled accordingto a variety of methods. FIG. 4 provides an illustrative heat pumpassembly method. First, a heat pump frame can be selected. The heat pumpframe can be selected based on the size of the heat pump and a varietyof other factors. In some instances, heat pumps can be combined toprovide a 30-ton capacity, a 60-ton capacity, or other desired capacity.

Compressors can be added to the heat pump frame (101). In manyembodiments, the compressor is a scroll compressor. The compressor canbe smooth in operation, compact, with good motor protection. The compactsize of such embodiments can permit the compressor to be built intorelatively small heat pump frames and modules that can be introduced toretrofit spaces through normal doorways. In some embodiments, thecompressor includes relatively few moving parts with better reliability.In some embodiments, the compressor is quieter and more energy efficientthan other compressors. An example of a compressor that is suitable forsome embodiments of the present invention is the Copeland Scroll ZR380.One advantage of using many such compressors according to embodiments ofthe present invention is the relatively quiet operation. Quiet operationof the compressor can enable a tolerable noise level in a mechanicalroom, even with open construction of some embodiments. This allows anoperator to readily see piping (e.g. to observe frosting, etc.) withoutthe removal of covers or other sound attenuation panels. One advantageof using many such compressors according to embodiments of the presentinvention is staging of capacity to achieve ideal compressor loading.Staging of compressors on individual refrigeration circuits enhancesreliability and performance of the HVAC system.

Condenser and evaporator heat exchangers can be added to the heat pumpframe (102). The evaporator and condenser heat exchangers can be pipedwith the relevant compressors (103) in common or separate refrigerantcircuits for the common hot and cold HVAC fluids. In some embodiments,components of the dryer shell can be silver soldered or Sil-Fos weldedto minimize leaks. In some embodiments, the core of the dryer can beremoved and replaced simply (e.g., without welding).

A pressure test can be conducted on the heat pump (104). The pressuretest can comprise adding nitrogen to the heat pump for a period of 12hours at a pressure of 250 psi. If the heat pump passes the pressuretest, it can be ready for the next step in the assembly process. If theheat pump fails, the failing joint can be fixed and the pressure testcan be repeated until it passes (104).

A control panel can be added to the heat pump frame (105). The controlpanel can be prefabricated. In some embodiments, the compressor mountingcan be accessed through a hinged electrical panel, thereby maintainingmaintenance access if the heat pump modules are connected side by side.

The various electrical components of the heat pump can be wired (106).The heat pump can then be subjected to an electrical test and safetycertification. If the heat pump passes the electrical test and safetycertification, the heat pump assembly process can be complete. If theheat pump fails the electrical test, the faulty wiring can be repaired,and the heat pump wiring and electrical components can be retested untilthe heat pump passes the electrical test and achieves safetycertification (106).

Referring again to FIG. 1A, as mentioned above, the HVAC system of FIG.1A includes a network of pipes and valves for distributing HVAC fluid tovarious components. The energy transfer components of FIG. 1A, which arediscussed in greater detail elsewhere herein, are connected to oneanother via a main loop 50. HVAC fluid can pass through the main loop 50and, depending on the circumstances, can also pass through one or moreof the energy transfer components. For example, in some heatingoperations, HVAC fluid can enter the main loop 50, pass through thesolar thermal panel 10 and/or the laundry heat transfer component 12and/or the waste water heat transfer component 14 and/or the groundenergy transfer component 16 and/or the geothermal well system 18 and/orthe outdoor air energy transfer component 20 and/or the exhaust heattransfer component 22 and/or the domestic cold water heat exchanger 24.As the HVAC fluid passes through the one or more energy transfercomponents during a heating operation, the HVAC fluid can pick up heatfrom the energy transfer components, thereby raising the temperature ofthe HVAC fluid. Depending on the circumstances, the HVAC fluid maybypass one or more of the energy transfer components (e.g., by closingthe valves to the energy transfer component(s)) as it passes through themain loop 50. In some embodiments, the HVAC fluid from one or moreenergy transfer components can be tied directly into the HVAC loops 40,42 feeding the conditioned space 6. This is shown in FIG. 1A for thesolar thermal panel 10, though it could be done for any individualenergy transfer component or combination of energy transfer components.

In heating operations, HVAC fluid can pass through the energy transfercomponent(s) on its way to the conditioned space 6 or on its way fromthe conditioned space 6. In some embodiments, HVAC fluid travels fromthe output of the heat pump's condenser heat exchanger 34 into theconditioned space 6, as well as into and through the main loop 50 (or toone or more individual energy transfer components), as well as back tothe input of the heat pump's condenser heat exchanger 34. In this way,the energy transfer component(s) can provide HVAC fluid to the heat pumpthat is warmer than it otherwise would be. In many such embodiments, theenergy transfer components can provide a larger change in temperature.In some embodiments, HVAC fluid travels from the output of the heatpump's condenser heat exchanger 34 through the main loop 50 (or to oneor more individual energy transfer components) to the conditioned space6 back to the input of the heat pump's condenser heat exchanger 34. Inthis way, the energy transfer component(s) can further warm HVAC fluidreceived from the heat pump 8. In some embodiments, HVAC fluid can passthrough one or more energy transfer components between exiting theconditioned space 6 and entering the heat pump 8 and also pass throughone or more energy transfer components between exiting the heat pump 8and entering the conditioned space 6. The control system of the heatpump 8 can be regulated to account for the presence of one or moreenergy transfer components.

The HVAC system of FIG. 1A includes a cooling loop 42 that can be usedin cooling operations. As shown in configuration 52, valves can be usedto channel HVAC fluid between the heat pump's condenser heat exchanger34 and the main loop 50 and/or between the heat pump's evaporator heatexchanger 38 and the main loop 50. In some embodiments, the valvingconfiguration 52 may occur individually for each energy transfercomponent. For example, HVAC fluid can enter the cooling loop 42 (and bedirected to the main loop 50 by the system valving 52), pass through theground energy transfer component 16 and/or the geothermal well system 18and/or the outdoor air energy transfer component 20 and/or the exhaustheat transfer component 22. In another example, HVAC fluid can enter thecooling loop 42 (and be directed to the main loop 50 by the systemvalving 52), pass through the solar thermal panel 10 and/or the laundryheat transfer component 12 and/or the waste water heat transfercomponent 14 and/or the domestic cold water heat exchanger 24. Inanother example, HVAC fluid can enter the cooling loop 42 (and bedirected to the main loop 50 by the system valving 52) and pass throughone energy transfer component while at the same time the HVAC fluid canenter the heating loop 40 (and be directed to a second loop by a valvingconfiguration) and pass through an energy rejection sink. Manyvariations are possible. Again, depending on the circumstances, the HVACfluid may bypass one or more of the energy transfer components (e.g., byclosing the valves 52 to the energy transfer component(s)) as it passesthrough the cooling loop 42 and the main loop 50.

As with heating operations, in cooling operations, HVAC fluid can passthrough the energy transfer component(s) which can reject heat away fromthe conditioned space 6. In some embodiments, HVAC fluid travels fromthe output of the heat pump's evaporator heat exchanger 38 to theconditioned space 6 through cooling loop 42 and (by way of the valvingconfiguration 52) the main loop 50 (or to one or more individual energytransfer components) back to the input of the heat pump's evaporatorheat exchanger 38. Energy transfer components that absorb energy fromthe HVAC fluid when their environments are warmer than the HVAC fluidbecome energy rejection components. In this way, the energy transfercomponent(s) can provide HVAC fluid to the heat pump that is cooler thanit otherwise would be. In some embodiments, HVAC fluid travels from theoutput of the heat pump's evaporator heat exchanger 38 through thecooling loop 42 and the main loop 50 (or to one or more individualenergy transfer components) to the conditioned space 6 back to the inputof the heat pump's evaporator heat exchanger 38. In this way, the energytransfer component(s) can further cool HVAC fluid received from the heatpump 8. In some embodiments, HVAC fluid can pass through one or moreenergy transfer components between exiting the conditioned space 6 andentering the heat pump 8 and also pass through one or more energytransfer components between exiting the heat pump 8 and entering theconditioned space 6. As noted above, the control system of the heat pump8 can be adjusted to account for the presence of one or more energytransfer components. Thus, in many embodiments, HVAC fluid can recoverenergy from, and/or reject energy to, one or more energy transfercomponents. HVAC systems can include various individual valveconfigurations enabling some of the energy transfer components to serveas energy recovery components and others to serve as energy rejectioncomponents. Many functional permutations and combinations are possible.

As discussed elsewhere herein, many embodiments can perform heatingoperations and cooling operations simultaneously. One or morecompressors can be activated, causing heat pump refrigerant to cyclethrough the heat pump components. The heat pump refrigerant can chillHVAC fluid at the evaporator heat exchanger 38 and simultaneously heatHVAC fluid at the condenser heat exchanger 34. In this way, heating andcooling different HVAC fluids can involve no more compressor work thanheating or cooling alone. HVAC systems can include a variety ofcomponents, which can be configured and operated in a variety of ways.Thus, embodiments of the present invention can reliably and efficientlyserve a wide variety of applications.

FIG. 1B shows an illustrative HVAC system similar to that of FIG. 1A. Ascan be seen, like the HVAC system of FIG. 1A, the HVAC system of FIG. 1Bincludes a heat pump 8, a main loop 50 with connections to variousenergy transfer components 10, 12, 14, 16, 18, 20, 22, 24, and a coolingloop 42 for heating and cooling zones 2, 4 of conditioned space 6. TheHVAC system of FIG. 1B can also provide heating for zones 54 and 56 ofconditioned space 6. Some or all of the HVAC fluid exiting the heat pump8 can be routed through a second heat pump 58 to further increase thetemperature of a second and separated HVAC fluid (often domestic hotwater) before it enters zones 54, 56 of conditioned space 6. Often, thekinds of zones that would benefit from passing through multiple heatpumps are zones that require HVAC fluid at significantly highertemperatures (e.g., higher temperature domestic hot water, process waterfor laundry use, process water for municipal or industrialapplications). When the HVAC fluid has passed through the second heatpump 58, the HVAC fluid can pass to zones 54, 56 through respectivedistribution boxes 62, 64.

HVAC systems according to embodiments of the present invention canarrange two or three or any suitable number of heat pumps (and/or groupsof heat pumps arranged in parallel) in a series relationship toprogressively increase the temperature of HVAC fluid passing throughthem. For example, a first heat pump can increase the temperature ofHVAC fluid from 15 degrees Fahrenheit to 60 degrees Fahrenheit. A secondheat pump can take that 60-degree HVAC fluid and increase itstemperature to 120 degrees Fahrenheit. A third heat pump can take that120-degree HVAC fluid and increase its temperature to 160 degreesFahrenheit. This sequence can continue until the temperature of the HVACfluid reaches a desired (e.g., selected, predetermined) level. In thisexample, three heat pumps increase the temperature of HVAC fluid from 15degrees Fahrenheit to 160 degrees Fahrenheit. Even if achieving thiskind of temperature difference with a single heat pump were feasible(which it most likely is not), the required energy input would besignificantly greater than it would be for the incremental approachdiscussed herein. In some embodiments, the temperature of domestic hotwater can be raised to 140 degrees Fahrenheit and process water to 160degrees Fahrenheit. Thus, in many instances, multiple heat pumpsarranged in a series relationship can provide additional functionality,improved system reliability, reduced wear on components, and increasedefficiency.

Arranging multiple heat pumps in a series relationship can providecertain advantages in some embodiments. In many embodiments, each heatpump that is arranged in a series relationship experiences less strainthan a single heat pump designed to achieve the same total temperaturedifference. In many such embodiments, the multiple heat pumps arrangedin series provide for increased durability and longevity. In someembodiments, heat pumps that are optimized for certain temperatureranges can be selected. For example, in the example provided above, thefirst heat pump can be configured for peak efficiency between 15 and 60degrees Fahrenheit, the second heat pump can be configured for peakefficiency between 60 and 120 degrees Fahrenheit, and the third heatpump can be configured for peak efficiency between 120 and 160 degreesFahrenheit. A heat pump can be optimized for a given temperature rangeby adjusting one or more of a variety of factors. For example, differentheat pump refrigerants can be used in each of the ranges, with each heatpump refrigerant having characteristics making it suitable for optimalefficiency within a given temperature range. Different heat pumps canoperate at different pressures and/or with different heat pumprefrigerant volumes to provide optimum operation within differenttemperature ranges. Though arranging multiple heat pumps in a seriesrelationship has been discussed in connection with progressivelyincreasing the temperature of HVAC fluid in heating operations, the samekind of arrangement can progressively decrease the temperature of HVACfluid in cooling operations.

As discussed herein, a fourth aspect of the present invention provides amethod of achieving a predetermined temperature difference in an HVACfluid. The method can include providing an initial heat pump (e.g., aheat pump discussed in connection with the first aspect or other heatpumps discussed herein) and a subsequent heat pump (e.g., a heat pumpdiscussed in connection with the first aspect or other heat pumpsdiscussed herein). The method can include connecting the initial heatpump and the subsequent heat pump in series. The method can includecirculating the HVAC fluid through the initial heat pump to achieve afirst temperature difference in the HVAC fluid. The method can includecirculating the HVAC fluid through the subsequent heat pump to achieve asecond temperature difference. The first and second temperaturedifferences can sum to be approximately equal to the predeterminedtemperature difference. The predetermined temperature difference can bea temperature increase (e.g., of 150F) or a temperature decrease (e.g.,of 150F).

Referring again to FIG. 1A, the illustrative HVAC system includes energytransfer components, as noted above. One of the energy transfercomponents shown in FIG. 1A is a solar thermal panel 10, which canassist the heat pump 8 in heating operations. The solar thermal panel 10of FIG. 1A includes four panels 30 that collect solar thermal energy(though any number of panels 30 are possible). Solar radiant energypasses through the glass cover of the panel and is entrapped within thepanel space. The solar radiant heat that accumulates in the panel isabsorbed and transferred from the panel space to the radiant fins. Theenergy absorbed by the fins dissipates to the attached piping at itscenter. The energy transferred to the piping can be absorbed by the HVACfluid that is passing through the pipes. In this way, HVAC fluid exitingthe solar thermal panel 10 can be warmer than HVAC fluid entering thesolar thermal panel 10, thereby reducing the amount by which the heatpump 8 must work to heat the relevant HVAC fluid to effectuate thedesired heating. In some embodiments, such as that of FIG. 1A, the solarthermal panel 10 can be connected to the main loop 50. In someembodiments, the solar thermal panel 10 can be connected directly to theheat pump 8. In some embodiments, the solar thermal panel 10 can beconnected to the domestic hot water supply, either instead of the HVACfluid or in addition to the HVAC fluid (e.g., by running alternatepiping circuits or the use of a heat exchanger on a separate solar panelpiping). Taking advantage of heat provided by the solar thermal panel 10can allow HVAC systems to perform significantly more efficiently andsustainably.

The HVAC system of FIG. 1A includes a laundry heat transfer component 12and a waste water heat transfer component 14 as energy transfercomponents. The laundry heat transfer component 12 can take advantage oflaundry exhaust (e.g., dryer exhaust) that is at a significantly highertemperature than the heat recovery HVAC fluid. In many buildings,laundry exhaust is channeled to the outside and into the surrounding airwithout the HVAC system taking advantage of its heat. The waste waterheat transfer component 14 can take advantage of waste water (e.g., fromlaundry process water, shower drains, water closets, sink drains, etc.)that is at a significantly higher temperature than the heat recoveryHVAC fluid. For example, the water running through shower drains isoften around 90 degrees Fahrenheit. In some embodiments, such as that ofFIG. 1A, both the laundry heat transfer component 12 and the waste waterheat transfer component 14 can be connected to the main loop 50. In someembodiments, either one or both of the laundry heat transfer component12 and the waste water heat transfer component 14 can be connecteddirectly to the heat pump 8. Recovering this heat and using it in abuilding's HVAC system can significantly offset heating loads, increaseheat pump efficiency, along with regenerating heat sources and providinga more sustainable system.

In many embodiments, the laundry heat transfer component 12 and thewaste water heat transfer component 14 can have substantially the sameflow-through structure. FIGS. 5A-5B show an example of such a structure.The flow-through heat transfer component 300 can include two coaxialtubes 302, 304. Laundry exhaust or waste water can pass through theinterior of the inner tube 304, through channel 306. In manyembodiments, the flow-through heat transfer component 300 can besubstituted for a section of piping in a laundry exhaust or a wastewater drainage system, with the inner diameter of tube 304 being smoothwalled and substantially the same as the inner diameter of the laundryexhaust or waste water drainage system pipe. In this way, the flow pathof the waste water or laundry exhaust can be substantially unimpeded bythe structure that channels the HVAC fluid through the flow-through heattransfer component 300. This can provide a significant advantage overconventional plate-and-frame components in that solid substances (e.g.,laundry lint, human waste, bones from kitchen drains, etc.) do not gettrapped in the HVAC structure, meaning that the heat can be recoveredwithout hindering the functionality of the laundry exhaust or wastewater systems.

The flow-through heat transfer component 300 of FIGS. 5A-5B includes aninlet pipe 308 and a corresponding inlet connector 309, as well as anoutlet pipe 312 and a corresponding outlet connector 313. The inlet andoutlet connectors 309, 313 can connect the flow-through heat transfercomponent 300 to HVAC pipes, thereby incorporating the flow-through heattransfer component 300 into an HVAC system. Once connected, HVAC fluidcan enter the flow-through heat transfer component 300 through the inletpipe 308 and then pass into the channel 310 between the exterior of theinner tube 304 and the interior of the outer tube 302. As the HVAC fluidflows within the channel 310 from the inlet pipe 308 toward the outletpipe 312, a barrier 314 guides HVAC fluid around and around the innertube 304 in a coil-like configuration. In many embodiments, this flowpath lengthens the amount of time the HVAC fluid is within theflow-through heat transfer component 300 and in thermal conductance withthe laundry exhaust or waste water. In many embodiments, this flow pathincreases the turbulence of the flowing HVAC fluid, thereby enhancingthe heat transfer of the HVAC fluid. When the HVAC fluid has completedits path through the channel 310 along the barrier 314, it exits theflow-through heat transfer component 300 through the outlet pipe 312.The HVAC fluid exiting the flow-through heat transfer component 300through the outlet pipe 312 can be at a significantly higher temperaturethan the HVAC fluid entering the flow-through heat transfer component300 through the inlet pipe 308.

The wall of the inner tube 304 can be configured to permit maximum heattransfer between the laundry exhaust or waste water and the HVAC fluid(e.g., can be made of thermally conductive material, such as a metal).The thickness of the wall of the inner tube 304 can relate to thethermal capacitance and absorptivity from the inner heat source, whichcould flow in either direction. The wall of the outer tube 302 can bemade of thermally insulating material (e.g., a type of plastic) or aninsulated metal, thereby inhibiting heat transfer between the HVAC fluidand the environment surrounding the flow-through heat transfer component300. Many factors can be controlled to facilitate maximum heat transfer,such as contact surface area, direction of source flow, HVAC fluid flowrate, source flow rate, HVAC fluid temperature, and so on. In this way,the heat from the laundry exhaust or the waste water can be recoveredand used in the HVAC system, allowing the HVAC system to perform moreefficiently and sustainably. In some embodiments, the flow-through heattransfer component 300 can be used in reverse to heat the fluid withinchannel 306. In some embodiments, one or both of the inner and outerflows may be reversed. The insulating and conducting materials can beinterchanged or made of the same material.

Referring again to FIG. 1A, the illustrative HVAC system can include aground energy transfer component 16. In certain ground conditions, it isadvantageous for the HVAC system to include pipes that exit the buildingand pass through a portion of the ground to take advantage of ambientground energy. In some embodiments, such as that of FIG. 1A, the groundenergy transfer component 16 can be connected to the main loop 50. Insome embodiments, the ground energy transfer component 16 can beconnected directly to the heat pump 8. Recovering this energy and usingit in a building's HVAC system can significantly increase efficiency,along with providing a more sustainable system.

FIG. 6 shows an illustrative ground energy transfer component 400,according to some embodiments of the present invention. Like theflow-through heat transfer component of FIGS. 5A-5B, the ground energytransfer component 400 of FIG. 6 includes two coaxial tubes 402, 404.The tubes 402, 404 are shown positioned in the ground 406. In someembodiments, the tubes 402, 404 can be positioned in water or in anyother suitable thermal mass. In many embodiments, the inner tube 402 ismade of a material that is relatively thermally insulative (e.g., HighDensity Polyethylene [HDPE] plastic piping). In many embodiments, theouter tube 404 is made out of material that is relatively thermallyconductive (e.g., stainless steel). The outer surface of the outer tube404 may have a thin moisture barrier. Reasons for making the inner tube402 of thermally insulative material and/or the outer tube 404 ofthermally conductive material are discussed in greater detail elsewhereherein.

The ground energy transfer component 400 of FIG. 6 includes an inletconnector 407 and an outlet connector 408. The inlet connector 407 canconnect to an inlet pipe 409 of an HVAC system, and the outlet connector408 can connect to an outlet pipe 410 of the HVAC system, therebyincorporating the ground energy transfer component 400 into the HVACsystem. In many embodiments, the inlet pipe 409 and the outlet pipe 410can be made of a plastic polymer, such as a high-density polyethylene.As noted above, the outer tube 404 is often made of metal, meaning thatthe inlet connector 407 and the outlet connector 408 often havecomponents that permit the polymer HVAC pipes to interface with themetal exterior of the ground energy transfer component.

In many embodiments, HVAC fluid can enter the ground energy transfercomponent 400 from the inlet pipe 409 through inlet connector 407 andcan exit through the outlet connector 408 into the outlet pipe 410. Insome embodiments, HVAC fluid can enter the ground energy transfercomponent 400 from the outlet pipe 410 through the outlet connector 408and exit through the inlet connector into the inlet pipe 409. In manyembodiments, the cross-sectional area of the connector by which the HVACfluid enters the ground energy transfer component can be smaller thanthe cross-sectional area of the corresponding HVAC pipe, therebyresulting in an increased flow velocity of the HVAC fluid. In manyembodiments, the flow volume of the HVAC fluid entering the groundenergy transfer component is substantially equal to the flow volume ofthe HVAC fluid exiting the ground energy transfer component.

When HVAC fluid enters the ground energy transfer component 400 from theinlet pipe 409 via the inlet connector 407, the HVAC fluid can flowdownwardly in the channel 412 between the outer surface of the innertube 402 and the inner surface of the outer tube 404. As the HVAC fluidflows downwardly within the channel 412, a barrier 414 guides the HVACfluid around and around the inner tube 402 in a coil-like configuration.In many embodiments, the barrier 414 serves to maintain the inner tube402 in a generally concentric relationship with the outer tube 404. Inmany embodiments, the barrier 414 can be constructed of deformabletubing (e.g., plastic or metal). In some embodiments, the tubing can bewrapped around the inner tube 402 to create coils in a desiredconfiguration. The tubing can be hot-air welded to the inner tube 402 tosubstantially prevent HVAC fluid from flowing straight down in thechannel 412 as opposed to along the barrier 414.

The HVAC fluid completes its path through the channel 412 along thebarrier 414 as it approaches the base 416 of the ground energy transfercomponent 400. As the HVAC fluid approaches and reaches the base 416, itenters the interior of the inner tube 402. In many embodiments, HVACfluid enters the interior of the inner tube 402 through holes 420. Insome embodiments, the lower end of the inner tube 402 can be open, whichcan permit HVAC fluid to enter the interior of the inner tube 402through that opening. In some embodiments, the inner tube 402 can haveboth holes 420 and an open lower end. In embodiments having holes 420and a closed lower end, the inner tube 402 can be connected to the base416 in a substantially rigid manner, thereby reducing the tensile stresson the plastic-to-metal or metal-to-metal adapters of the inletconnector 407 and the outlet connector 408. In many embodiments, thecollective cross-sectional area of the holes 420 is greater than thecross sectional area of the interior of the inner tube 402, therebypermitting ease of passage. In some embodiments, the holes 420 can bearranged approximately symmetrically about the inner tube 402. In thisway, the flow momentum of the HVAC fluid can be balanced due to flowthrough the each hole 420 being countered by flow through one or moreopposite holes 420.

The HVAC fluid then flows relatively laminarly upward in the interior ofthe inner tube 402. The cross-sectional area of the interior of theinner tube 402 can be significantly greater than the cross-sectionalarea within the channel 412. In this way, flow velocity within the innertube 402 can be reduced, thereby producing a more laminar flow. In manyembodiments, the HVAC fluid contacts significantly less surface of theground energy transfer component on the upward path than on the downwardpath. Similarly, in most embodiments, the HVAC fluid can flowsubstantially unimpeded by other surfaces within the inner tube 402,thereby producing a more laminar flow. The upward path is also generallya significantly shorter distance, without spiraling around the groundenergy transfer component 400. The HVAC fluid then exits the groundenergy transfer component 400 through the outlet connector 408 and flowsback into the outlet pipe 410. In such an embodiment, because thevertical temperature gradient of the surrounding ground 406 is oppositeto that of the HVAC fluid in channel 412—during both heating andcooling—the ground energy transfer component 400 can serve as across-flow heat exchanger with the ground or ground fluid.

As referenced above, the HVAC fluid can thermally react with the ground406 while in the ground energy transfer component 400. The HVAC fluidwithin channel 412, as guided by barrier 414, can thermally react withthe ground. In many embodiments, this flow path increases the amount oftime that the HVAC fluid is in thermal communication with thesurrounding ground 406. In some embodiments, the momentum of the HVACfluid as it flows along the barrier 414 causes it to crash against theinterior of the outer tube 404. This turbulence can result in greaterheat transfer between the HVAC fluid and the surrounding ground 406.Turbulence can be increased by providing increased flow velocity of theHVAC fluid; subjecting the HVAC fluid to more frictional forces due tocontacting the barrier 414, the inner tube 402, and the outer tube 404;and/or by subjecting the HVAC fluid to a greater degree of centripetalforce. As the HVAC fluid contacts the barrier 414, the inner tube 402,and the outer tube 404, it should be noted that the outer tube 404provides a larger surface area for heat transfer to occur and that theHVAC fluid is contacting at the peak of its centripetal velocityprofile.

In some instances, the HVAC fluid recovers heat from the ground 406,resulting in HVAC fluid that is warmer near the base 416 than the HVACfluid near the inlet connector 407. In some instances, the HVAC fluiddissipates heat to the ground 406, resulting in HVAC fluid that iscooler near the base 416 than the HVAC fluid near the inlet connector407. Generally, the HVAC fluid recovers heat from the ground 406 whenthe ground 406 is warmer than the HVAC fluid, and the HVAC fluiddissipates heat to the ground 406 when the ground 406 is cooler than theHVAC fluid. In many instances, the HVAC fluid recovers heat from theground when the HVAC system is heating, and the HVAC fluid dissipatesheat to the ground when the HVAC system is cooling. The wall of theouter tube 404 can be configured to permit maximum heat transfer betweenthe HVAC fluid and the ground 406 (e.g., can be made of thermallyconductive material, such as stainless steel).

The heat transfer properties can be enhanced by the surface propertiesof the barrier 414, the angle of slope (pitch) of the barrier 414, thesize of the passageway between two sections of the barrier 414, the flowrate of the HVAC fluid, the centrifugal forces, other factors, orcombinations thereof. In some embodiments, the spaces between coils ofthe barrier 414 can be non-uniform. For example, a single ground energytransfer component can have some coils that are spaced further apart(e.g., in ground with a higher recovery rate, such as an undergroundstream; in ground with a convective heat transfer component, such asflowing waste water) and other coils that are closer together (e.g., inordinary ground with a lower heat recovery rate). In this way, theground energy transfer component 400 can be tuned to the groundconditions by adjusting the pitch of the barrier 414.

In many embodiments, the HVAC fluid in the interior of the inner tube402 can be generally thermally insulated, resulting in a relativelyconstant temperature within the interior of the inner tube 402. The wallof the inner tube 402 can be made of thermally insulating material,thereby inhibiting heat transfer between the HVAC fluid flowing throughchannel 412 and the HVAC fluid flowing in the interior of the inner tube402. The spiraling flow path can create a velocity profile at theinterface between the inner tube 402 and the HVAC fluid is relativelysmall, thereby resulting in less heat transfer between the HVAC fluid inchannel 412 and the HVAC fluid in the interior of the inner tube 402.

Insulating the HVAC fluid within the interior of the inner tube 402 cangenerally preserve the effect of the heat transfer that occurred whileHVAC fluid was flowing through channel 412. In some embodiments, a smallamount of heat may transfer between HVAC fluid flowing within the innertube 402 to HVAC fluid flowing within the outer tube 404. In suchembodiments, the heat is transferred within the system, meaning that theheat is not lost to the surrounding environment. Providing both a heattransfer path and a return insulated path (or vice versa) can provideseveral advantages, such as improving the total heat transfer, reducingthe volume of fluid, and improving the HVAC system response rate. Inthis way, embodiments of the ground energy transfer component 400 can beeasily integrated into HVAC systems. The ground energy transfercomponent 400 can aid in recovering energy from the ground 406 (e.g.,ground having the above-mentioned ground conditions) to be used in HVACsystems.

In some embodiments, the flow path through the ground energy transfercomponent 400 can be reversed. HVAC fluid can enter the ground energytransfer component 400 from the outlet pipe 410 via the outlet connector408, flow downwardly within the interior of the inner tube 402 towardbase 416, flow back upwardly through channel 412 (while recovering heatfrom the ground 406 or dissipating heat to the ground 406), and thenexit the ground energy transfer component 400 to the inlet pipe 409 viathe inlet connector 407.

Embodiments of the ground energy transfer component 400 can provide oneor more of the following advantages. Some embodiments are closedsystems, meaning that they can accommodate HVAC fluids such asantifreeze while remaining environmentally friendly. As closed systems,the HVAC fluid is not affected by ground or water minerals. In suchembodiments, the welds in the outer tube and base can be air tight, ascan the relevant connectors. Some embodiments provide more efficientheat transfer as compared with some closed geothermal wells. Someembodiments provide equal or better heat transfer as compared with opengeothermal wells, but without environmental exposure to the ground ormineral exposure to the HVAC system. This increased efficiency canpermit ground energy transfer components that are significantly shorterthan geothermal wells. For example, many ground energy transfercomponent embodiments are less than 50 feet long. Many ground energytransfer component embodiments come in standard pipe lengths (e.g., 21feet, etc.). Many ground energy transfer component embodiments arecapable of fitting within a single (e.g., 6-inch diameter) bore hole.Some embodiments have a significantly smaller footprint than mostconventional horizontal geothermal wells, some of which may be buried inrelatively shallow ground. Some embodiments, such as those having outertubes made of mill grade stainless steel, can provide significantlyenhanced durability. Some embodiments can be used in connection withrelatively small pumping heads and/or can operate at relatively low flowrates. Some embodiments are relatively inexpensive and/or simple tomanufacture (e.g., due to the simple construction, the wide availabilityof base materials, etc.). Some embodiments provide the above-noted heattransfer benefits without diminishing the appearance of the buildinginto which they are incorporated (e.g., they have no rejection towers,propane tanks, exhaust stacks, etc.).

Many ground energy transfer components can be installed with relativeease. For example, a 4-inch hollow-stem auger can be inserted into theground at a desired depth. The ground energy transfer component can thenbe slid into the interior of the auger. The auger can then be removedfrom the hole, leaving the ground energy transfer component intact. Thiscan permit installation in even wet ground conditions. It can alsoreduce or eliminate the need for holding the hole open duringinstallation. In installing ground energy transfer components in rock, a3.7-inch cored hole can be used, thereby reducing the required amount ofrock drilling. In many instances, the ground energy transfer componentcan be pre-fabricated, thereby simplifying on-site installation. Avariety of installation methods can be employed.

Some HVAC systems include multiple ground energy transfer components400. Multiple ground energy transfer components are arranged in seriesin some systems. Multiple ground energy transfer components are arrangedin parallel in some systems. Some parallel arrangements provideadvantages, such as reduced resistance to flow in the HVAC system andthus lower pumping costs.

Some embodiments of the ground energy transfer component can be used inapplications other than HVAC systems. Examples include heaters forintakes of hydroelectric power dams, industrial processes, and othersuitable applications.

Referring again to FIG. 1A, one of the energy transfer components of theillustrative HVAC system is a geothermal well system 18. The geothermalwell system 18 can channel HVAC fluid down deep below the surface of theearth. In many embodiments, the geothermal well system 18 includes oneor more loops 44, each comprising two pipes connected on their lowerends by a connector. Often, the loops 44 extend roughly 150-400 feetbelow the surface of the earth, where the temperature remains relativelyconstant. For much of the northern United States, this temperature isaround 45 degrees Fahrenheit. The geothermal well system 18 can be madeof thermally conductive material, thereby encouraging heat transferbetween the HVAC fluid running through the geothermal well system 18 andthe ground. In many embodiments, the geothermal well system 18 can bemade of plastic pipe, which can have limited thermal conductivity.Generally, in heating operations, heat can be transferred from theground to the HVAC fluid, and in cooling operations, heat can betransferred from the HVAC fluid to the ground. In some embodiments, suchas that of FIG. 1A, the geothermal well system 18 can be connected tothe main loop 50. In some embodiments, the geothermal well system 18 canbe connected directly to the heat pump 8. In this way, the HVAC systemcan take advantage of the relatively constant temperature beneath theearth's surface, allowing the HVAC system to perform more efficientlyand sustainably.

One of the energy transfer components of the illustrative HVAC system ofFIG. 1A is an outdoor air energy transfer component 20. In manyembodiments, it is advantageous to channel HVAC fluid through pipes thatare exposed to outdoor ambient air. For example, in cooling the interiorplaying surface of an ice arena (e.g., to 20 degrees Fahrenheit) duringpeak winter and/or during cold “off-electrical peak” evenings when theair is colder than 20 degrees Fahrenheit, the HVAC system can dissipatesignificant amounts of heat to the outdoor ambient air while chillingthe HVAC fluid used for cooling the interior playing surface of an icearena. During the times when making ice with compressor work, the warmHVAC fluid can dissipate its heat from the compressors. In someembodiments, the outdoor air energy transfer component 20 is a closedloop that conserves water and does not evaporate it. The HVAC fluid canpass through the outdoor air energy transfer component 20, and a fan 46can blow outdoor ambient air across the pipes containing HVAC fluid. Insome embodiments, such as that of FIG. 1A, the outdoor air energytransfer component 20 can be connected to the main loop 50. In someembodiments, the outdoor air energy transfer component 20 can beconnected directly to the heat pump 8. In this way, the HVAC system cantake advantage of the outdoor ambient air, allowing the HVAC system toperform more efficiently and sustainably. In some situations, theoutdoor air energy transfer component 20 can be used in enclosed spacesthat simultaneously achieve a desired effect on the ambient air and theHVAC fluid.

One energy transfer component of the illustrative HVAC system of FIG. 1Ais an exhaust heat transfer component 22. In many instances, variouskinds of exhaust (e.g., building relief air, parking garage exhaust,general exhaust, non-grease kitchen exhaust, kiln exhaust, etc.) isremoved buildings without taking advantage of the exhaust's thermalproperties. HVAC fluid can be channeled around a coil within the exhaustheat transfer component 22. Exhaust can pass by the coil, therebythermally reacting with the HVAC fluid. In this way, HVAC fluid exitingthe exhaust heat transfer component 22 can be warmer than HVAC fluidentering the exhaust heat transfer component 22, thereby reducing theamount by which the heat pump 8 must heat the relevant HVAC fluid toeffectuate the desired heating. In some embodiments, such as that ofFIG. 1A, the exhaust heat transfer component 22 can be connected to themain loop 50. In some embodiments, the exhaust heat transfer component22 can be connected directly to the heat pump 8. In some embodiments,the exhaust heat transfer component 22 can be connected to HVAC fluidthat is warmer than the exhaust air in order to reject heat from theHVAC system. In this way, the HVAC system can take advantage of thethermal properties of the otherwise unused exhaust, allowing the HVACsystem to perform more efficiently and sustainably.

One energy transfer component of the illustrative HVAC system of FIG. 1Ais a domestic cold water heat exchanger 24. In many instances, thedomestic cold water provided to a building (e.g., from a municipality)is warmer than it needs to be and/or warmer than desired. For example,domestic cold water is often provided at 45 degrees Fahrenheit andwarmer, while cold water coming out of the tap is commonly (and oftenpreferably) only 37 degrees Fahrenheit. Accordingly, the domestic coldwater heat exchanger 24 can reduce the temperature of the domestic coldwater while providing the excess heat to the HVAC fluid flowing throughthe domestic cold water heat exchanger 24. In this way, HVAC fluidexiting the domestic cold water heat exchanger 24 can be warmer thanHVAC fluid entering the domestic cold water heat exchanger 24, therebyreducing the amount by which the heat pump 8 must heat the relevant HVACfluid to effectuate the desired heating. In this way, the domestic coldwater can be made biologically safer and can be made usable for coolingapplications. In some embodiments, such as that of FIG. 1A, the domesticcold water heat exchanger 24 can be connected to the main loop 50. Insome embodiments, the domestic cold water heat exchanger 24 can beconnected directly to the heat pump 8. In this way, the HVAC system cantake advantage of the heat provided by cooling the domestic cold water,allowing the HVAC system to perform more efficiently and sustainably.

In the illustrative HVAC system of FIG. 1A, the above-mentioned networkof pipes and valves can distribute temperature-controlled HVAC fluid tothe illustrated building zones 2, 4. Before the HVAC fluid flows to thebuilding zones 2, 4, the HVAC fluid can flow through respectivedistribution boxes 26, 28. As discussed elsewhere herein, many buildingshave several zones, such as 20, 30, 40, or more zones. For example, in ahotel, each room can constitute its own zone. In many embodiments of thepresent invention, one distribution box is provided for each buildingzone. The distribution boxes 26, 28 can provide more precise temperaturecontrol to the building zones 2, 4. Moreover, as is discussed elsewhereherein, many distribution boxes 26, 28 are indeed modular in that theycan be easily exchanged in their entirety if one or more of thecomponents therein needs to be repaired or replaced. In this way, therelevant building zone can be isolated from the HVAC system (e.g., byshutting inlet and outlet HVAC fluid valves) for only the relativelyshort period of time required to exchange the distribution box, asopposed to isolating that building zone for the often much longer periodof time required to repair or replace the relevant component(s). Withthe distribution box removed from the HVAC system, the relevantcomponent(s) can be repaired or replaced in a shop location, therebypreparing the distribution box to be reintroduced to an HVAC system. Thedistribution box can be reintroduced to the same HVAC system (in thesame or different location) or in an entirely different HVAC system.

In many instances, it is advantageous to build a complete distributionbox in a setting more conducive to construction (e.g., a machine shop),as opposed to interconnecting the various components at the same time asinstalling the HVAC system. In many such instances, the setting moreconducive to the construction may be located remotely from the HVACsystem installation site. The setting may employ more specificallytrained or alternately waged people to perform the task.

FIG. 7 shows an illustrative distribution box 500, according to someembodiments of the present invention. As shown, the distribution box 500can include a hot HVAC fluid inlet pipe 502, a cold HVAC fluid inletpipe 504, a hot HVAC fluid outlet pipe 506, and a cold HVAC fluid outletpipe 508. Each of the inlet and outlet pipes 502, 504, 506, 508 can havea corresponding connector. Connector 514 can be connected to the hotHVAC fluid inlet pipe 502, connector 516 can be connected to the coldHVAC fluid inlet pipe 504, connector 518 can be connected to the hotHVAC fluid outlet pipe 506, and connector 520 can be connected to thecold HVAC fluid outlet pipe 508. The distribution box 500 can include afan coil supply pipe 510 and a fan coil return pipe 512. Both of the fancoil pipes 510, 512 can have a corresponding connector, with connector522 being connected to the fan coil supply pipe 510 and connector 524being connected to the fan coil return pipe 512. The fan coil pipes 510,512 can enable the distribution box 500 to be connected to a fan coiland/or to various HVAC terminal devices.

The connectors 514, 516, 518, 520, 522, 524 of the distribution box 500can connect to HVAC pipes, thereby incorporating the distribution box500 into an HVAC system. In many embodiments, the connectors 514, 516,518, 520, 522, 524 of the distribution box 500 can be configured topermit the distribution box 500 to be connected to, and disconnectedfrom, the remainder of the HVAC system relatively quickly.

As noted, HVAC fluid can flow through the distribution box 500. HVACfluid can flow into the distribution box 500 via the hot HVAC fluidinlet pipe 502 and/or the cold HVAC fluid inlet pipe 504. A valve 526can permit either hot HVAC fluid coming from the hot HVAC fluid inletpipe 502 or cold HVAC fluid coming from the cold HVAC fluid inlet pipe504 to pass through to pump 528. Pump 528 can pump the relevant HVACfluid through the fan coil supply pipe 510 and into a fan coil. In someembodiments, the HVAC fluid can flow into the fan coil without the needof pump 528 (e.g., if the rest of the HVAC system is designed to providethe requisite pressure). After passing through the fan coil, the HVACfluid can re-enter the distribution box via the fan coil return pipe512. A valve 530 can channel the HVAC fluid out of the distribution box500 via either the hot HVAC fluid outlet pipe 506 or the cold HVAC fluidoutlet pipe 508. The valves 526 and 530 can be configured such that hotHVAC fluid and cold HVAC fluid do not mix. Hot HVAC fluid from HVACfluid inlet pipe 502 can return to the hot HVAC fluid at hot HVAC fluidoutlet pipe 506. Cold HVAC fluid from cold HVAC fluid pipe 504 canreturn to the cold HVAC fluid at cold HVAC fluid outlet pipe 508.

A controller 532 can control various aspects of the distribution box500. The controller 532 can be in electrical communication with one ormore inputs, such as thermostat 534. Thermostat 534 can be positionedwithin the appropriate zone. One or more individuals within the zone canmanually adjust conditions of the zone via thermostat 534, or thermostat534 can operate according to various pre-selected conditions. Otherinputs that can be in electrical communication with the controller 532include various sensors. For example, a temperature sensor can bepositioned in the fan coil supply pipe 510 such that the temperaturesensor can inform the controller 532 of the temperature of the HVACfluid entering the fan coil. Several other inputs are used in variousembodiments.

Based on information provided by one or more inputs, the controller 532can control various aspects of the distribution box 500. For example,the controller 532 can instruct valve 526 to permit only hot HVAC fluidto pass through to the pump 528 (e.g., during a heating operation) or topermit only cold HVAC fluid to pass through to the pump 528 (e.g.,during a cooling operation). In some instances, the controller 532 cancontrol the flow rate and/or displacement of the pump 528. In someembodiments, the controller 532 can instruct valve 530 to channelreturning HVAC fluid through the hot HVAC fluid outlet pipe 506 (e.g.,during a heating operation) or through the cold HVAC fluid outlet pipe508 (e.g., during a cooling operation). In some instances, thecontroller 532 can (digitally) instruct the blower of the fan coil tovarious pre-wired stages of speed or it can instruct the blower of thefan coil to any increment of speed on a variable (analogue) signal.

Like other controllers discussed herein, the controller 532 can beimplemented in digital electronic circuitry, integrated circuitry,specially designed ASICs (application specific integrated circuits),computer hardware, firmware, software, electric relays and switchesand/or combinations thereof. These various implementations can includeimplementation in one or more computer programs that are executableand/or interpretable on a programmable system including at least oneprogrammable processor, which may be special or general purpose, coupledto receive data and instructions from, and to transmit data andinstructions to, a storage system, at least one input device, and atleast one output device. These various implementations can includerelays and switches from a remote controller device (e.g., a thermostat)wired or wirelessly connected to the assembled body of an embodiment ofthe invention.

In many instances, the controller can be connected via a network (e.g.,a LAN, a WAN, the Internet, etc.) to other components of the HVACsystem. Examples of components to which the controller 532 may beconnected include controllers of other distribution boxes, controllersfor one or more of the various energy transfer components, controllersfor one or more heat pump, operator input devices/stations, zone inputsensors (e.g., a sensor to indicate whether the zone has transitionedfrom a closed system to an open system, such as through the opening of adoor or window), and other suitable components. In this way, an operator(e.g., a hotel employee at the front desk) can provide instructions tothe controller 532, such as whether the zone is occupied, one or moreset-point temperatures for the zone, changes to the set-pointtemperature or limit set points, changes to the actual temperature,whether to cease heating/cooling in the zone, and so on. In this way,the operator can remotely control various HVAC conditions within a givenzone with relative ease.

In many HVAC system embodiments in which a controller and correspondingpump(s) and valve(s) regulate the HVAC fluid entering the fan coil, theHVAC fluid can enter only one coil within the fan box, as opposed to twoseparate coils (one for cold HVAC fluid and the other for hot HVACfluid). FIG. 8 illustrates such a system. Such a system can provide oneor more of several advantages. Some such systems can accommodate potablewater as the HVAC fluid in that there is a significantly lowerlikelihood that water will remain stagnant in the fan coil. Thecontroller can cause the pump to regularly circulate the water in andthrough the fan box, thereby preventing the water from becomingstagnant. This contrasts with many two-coil systems in which water canremain stagnant for six months or more (e.g., hot water in the hot watercoil during a long cooling season), leading to contamination and/orunacceptable temperatures. Regularly circulating the water candramatically reduce the risk of contamination of the potable HVAC fluid,as well as maintain the water at an acceptable temperature (e.g., hotwater above 115 degrees Fahrenheit). Some such systems can reduce thelikelihood of simultaneously heating and cooling a zone, therebyreducing inefficiencies. Some such systems incorporate one larger sizecoil, which can accomplish heating or cooling with HVAC fluid at loweror higher temperatures, respectively. Some such systems can operate inthe absence of the heat pump in some circumstances (e.g., when the oneor more energy transfer components are capable of providing HVAC fluidat the desired temperatures). Some such systems can operate effectivelyby one or more smaller fans (e.g., having only one coil as opposed totwo coils can reduce the static pressure drop that the fan mustovercome, allowing the fan to be smaller and often using less energy andproducing less noise).

Referring again to FIG. 7, in some embodiments, the distribution box 500is configured to accommodate potable water. Valves, pumps, and othercomponents can be constructed out of materials (e.g., bronze, stainlesssteel, etc.) that do not erode in such a way as to contaminate thepotable water. Such systems can include a bronze body circulating pump(e.g., Grundfos UP15-42 B7 or UP26-96 BF). The pumps can be 100% leadfree circulators suitable for potable water systems with 145 psi maximumoperating pressure and 176 degrees Fahrenheit maximum fluid temperaturein a 104 degrees Fahrenheit maximum ambient temperature. In someembodiments, the pumps can accommodate water from just above freezing(e.g., 35.6 degrees Fahrenheit) up to approximately 230 degreesFahrenheit. Some embodiments include a composite impeller suitable forpotable water. Many other variations are possible. Systems thataccommodate potable water often circulate the water to preventstagnation, whether or not circulation is needed for HVAC purposes.

Distribution components similar to the distribution box 500 of FIG. 7can be incorporated into other locations in HVAC systems. For example,some energy transfer components can be used in both heating and coolingoperations. Examples from FIG. 1A include the ground energy transfercomponent 16, the geothermal well system 18, the outdoor air energytransfer component 20, and the exhaust heat transfer component 22. Adistribution box can be connected between such energy transfercomponents and, e.g., the main loop 50. Such a distribution box caninclude one or more valves, controllable by a controller, that channeleither hot HVAC fluid (e.g., during heating operations) or cold HVACfluid (e.g., during cooling operations) through the energy transfercomponent. Some distribution boxes that are incorporated into otherlocations in HVAC systems can have similar characteristics to thedistribution box of FIG. 7, meaning that they can be swapped out quicklyand efficiently.

In the foregoing detailed description, the invention has been describedwith reference to specific embodiments. However, it may be appreciatedthat various modifications and changes can be made without departingfrom the scope of the invention as set forth in the appended claims.Thus, some of the features of preferred embodiments described herein arenot necessarily included in preferred embodiments of the invention whichare intended for alternative uses.

1. A high-efficiency heat pump, comprising: (a) a frame; (b) a firstcircuit supported by the frame and configured to circulate a firstrefrigerant; (c) a first compressor supported by the frame and connectedto the first circuit, the first compressor being configured to (i)receive the first refrigerant from the first circuit, (ii) increasepressure of the first refrigerant, and (iii) provide the higher-pressurefirst refrigerant back to the first circuit; (d) a condenser heatexchanger supported by the frame and connected to the first circuit, thecondenser heat exchanger being configured to (i) receive thehigher-pressure first refrigerant from the first circuit, (ii) transferenergy from the higher-pressure first refrigerant to a first HVAC fluidpassing through the condenser heat exchanger, and (iii) provide thefirst refrigerant back to the first circuit; (e) a first electronicexpansion valve supported by the frame and connected to the firstcircuit, the first electronic expansion valve being configured to (i)receive the first refrigerant from the first circuit, (ii) decreasepressure of the first refrigerant, and (iii) provide the lower-pressurefirst refrigerant back to the first circuit; (f) an evaporator heatexchanger supported by the frame and connected to the first circuit, theevaporator heat exchanger being configured to (i) receive thelower-pressure first refrigerant from the first circuit, (ii) transferenergy from a second HVAC fluid passing through the evaporator heatexchanger to the lower-pressure first refrigerant, and (iii) provide thefirst refrigerant back to the first circuit; and (g) a controller inelectronic communication with the first electronic expansion valve, thecontroller being configured to control operation of the first electronicexpansion valve.
 2. The high-efficiency heat pump of claim 1, furthercomprising: (h) a second circuit supported by the frame and configuredto circulate a second refrigerant; (i) a second compressor supported bythe frame and connected to the second circuit; and (j) a secondelectronic expansion valve supported by the frame and connected to thesecond circuit, wherein the second compressor is configured to (i)receive the second refrigerant from the second circuit, (ii) increasepressure of the second refrigerant, and (iii) provide thehigher-pressure second refrigerant back to the second circuit, whereinthe condenser heat exchanger is further configured to (i) receive thehigher-pressure second refrigerant from the second circuit, (ii)transfer energy from the higher-pressure second refrigerant to HVACfluid passing through the condenser heat exchanger, and (iii) providethe second refrigerant back to the second circuit, wherein the secondelectronic expansion valve is configured to (i) receive the secondrefrigerant from the second circuit, (ii) decrease pressure of thesecond refrigerant, and (iii) provide the lower-pressure secondrefrigerant back to the second circuit, wherein the evaporator heatexchanger is further configured to (i) receive the lower-pressure secondrefrigerant from the second circuit, (ii) transfer energy from HVACfluid passing through the evaporator heat exchanger to thelower-pressure second refrigerant, and (iii) provide the secondrefrigerant back to the second circuit, and wherein the controller is inelectronic communication with the first electronic expansion valveand/or the second electronic expansion valve, the controller beingconfigured to control operation of the first electronic expansion valveand/or the second electronic expansion valve.
 3. The high-efficiencyheat pump of claim 2, wherein the controller is configured to modulatethe first and second compressors. 4.-5. (canceled)
 6. Thehigh-efficiency heat pump of claim 1, wherein the first electronicexpansion valve is configured to communicate electronically with anoperator and/or a remote controller through a network.
 7. (canceled) 8.The high-efficiency heat pump of claim 1, wherein the first expansionvalve is controllable to (A) simultaneously heat the first HVAC fluid toa temperature above 100F and cool the second HVAC fluid to a temperaturebelow 10F in a first season and (B) simultaneously heat the first HVACfluid to a temperature above 160F and cool the second HVAC fluid to atemperature below 40F in a second season.
 9. A method of efficientlyheating and/or cooling HVAC fluid, comprising: (a) providing ahigh-efficiency heat pump that includes: (i) a frame, (ii) a firstcompressor, a condenser heat exchanger, a first electronic expansionvalve, and an evaporator heat exchanger, each supported by the frame,and (iii) a first circuit supported by the frame and configured tocirculate a first refrigerant through the first compressor, thecondenser heat exchanger, the first electronic expansion valve, and theevaporator heat exchanger; (b) circulating a first HVAC fluid throughthe condenser heat exchanger or the evaporator heat exchanger; (c)activating the first compressor to heat the first HVAC fluid if thefirst HVAC fluid is circulating through the condenser heat exchanger orto cool the first HVAC fluid if the first HVAC fluid is circulatingthrough the evaporator heat exchanger; and (d) controlling the firstelectronic expansion valve to control heating of the first HVAC fluid ifthe first HVAC fluid is circulating through the condenser heat exchangeror to control cooling of the first HVAC fluid if the first HVAC fluid iscirculating through the evaporator heat exchanger.
 10. The method ofclaim 9, further comprising (e) circulating a second HVAC fluid throughwhichever of the heat exchangers the first HVAC fluid is not circulatingthrough, wherein activating the first compressor simultaneously heatsthe HVAC fluid in the condenser heat exchanger to a temperature above125F and cools the HVAC fluid in the evaporator heat exchanger to atemperature below 35F.
 11. The method of claim 10, wherein activatingthe first compressor simultaneously heats the HVAC fluid in thecondenser heat exchanger to a temperature above 130F and cools the HVACfluid in the evaporator heat exchanger to a temperature below 30F. 12.The method of claim 9, wherein the heat pump further includes: (iv) asecond compressor and a second electronic expansion valve, bothsupported by the frame, and (v) a second circuit supported by the frameand configured to circulate a second refrigerant through the secondcompressor, the condenser heat exchanger, the second electronicexpansion valve, and the evaporator heat exchanger.
 13. The method ofclaim 12, further comprising activating both the first compressor andthe second compressor to heat the first HVAC fluid if the first HVACfluid is circulating through the condenser heat exchanger or to cool thefirst HVAC fluid if the first HVAC fluid is circulating through theevaporator heat exchanger.
 14. (canceled)
 15. The method of claim 12,wherein the first refrigerant and the second refrigerant are differentrefrigerants having different properties.
 16. The method of claim 9,wherein controlling the first electronic expansion valve comprisesremotely controlling the first electronic expansion valve.
 17. Themethod of claim 16, wherein remotely controlling the first electronicexpansion valve comprises controlling operation of the first electronicexpansion valve based on input from one or more sensors of an HVACsystem that incorporates the heat pump. 18-28. (canceled)
 29. A methodof achieving a predetermined temperature difference in an HVAC fluid,comprising: (a) providing an initial heat pump and a subsequent heatpump; (b) connecting the initial heat pump and the subsequent heat pumpin series; (c) circulating the HVAC fluid through the initial heat pumpto achieve a first temperature difference in the HVAC fluid; and (d)circulating the HVAC fluid through the subsequent heat pump to achieve asecond temperature difference, wherein the first and second temperaturedifferences sum to be approximately equal to the predeterminedtemperature difference.
 30. The method of claim 29, wherein the initialheat pump and/or the subsequent heat pump includes a controllableelectronic expansion valve configured to control performance of theinitial heat pump and/or the subsequent heat pump.
 31. The method ofclaim 30, wherein the controllable electronic expansion valve isremotely controllable.
 32. The method of claim 29, wherein the initialheat pump and/or the subsequent heat pump comprise two or more heat pumpunits.
 33. (canceled)
 34. The method of claim 29, wherein thepredetermined temperature difference is a temperature increase of 150F.35. (canceled)
 36. The method of claim 29, wherein the predeterminedtemperature difference is a temperature decrease of 150F.
 37. (canceled)38. The method of claim 29, further comprising (e) circulating a firstrefrigerant through the initial heat pump and circulating a secondrefrigerant through the subsequent heat pump, wherein the firstrefrigerant and the second refrigerant are different refrigerants havingdifferent properties.